Device for cleaning food with ozone water, and method of cleaning food using cleaning device

ABSTRACT

A food washing apparatus of the invention includes an ozonized water generator ( 10 ), a cylindrical washing tank ( 1 ) in which the food materials are put and which can rotate to wash the food materials, a drainage part ( 4 ) formed at a part of the washing tank ( 1 ) and including openings to such a degree that water passes through and the food materials do not pass through, and wash water pipings ( 2, 9 ) which are inserted and disposed in the washing tank ( 1 ) in an axial direction and in which water spray holes ( 2   a   , 2   a ) for spraying wash water including at least ozonized water are formed, and while at least one part of the wash water sprayed from the wash water pipings ( 2, 9 ) is draind from the washing tank ( 1 ) every rotation of the washing tank ( 1 ), washing of the food materials is performed. Further, there is also a method in which a receiving tank ( 8 ) for wash water drained from the washing tank ( 1 ) is provided, and at least one part of the wash water in the receiving tank ( 8 ) is returned to an inlet side of the ozonized water generator ( 10 ) to perform cyclic use of the wash water.

TECHNICAL FIELD

The present invention relates to a food materials washing apparatuswhich performs effective sterilization and washing of vegetables to beeaten raw, or grains, tubers, or seeds (including ones for gardening andfor farming) or nuts etc. (hereinafter simply abbreviated to “foodmaterials”), and a washing method using the apparatus.

BACKGROUND ART

Conventionally, a method of cutting vegetables to be eaten raw intopredetermined sizes and transporting or selling them has been carriedout. This method is carried out when vegetables for salad to be eatenraw are cut into predetermined sizes, are divided into small pieces forsingle persons, are packed and are sold, or vegetables cut in aprocessing plant are transported to related restaurants. In recentyears, the demand tends to increase. Besides, needs for a treatment ofenabling the long preservation of grains, tubers, or seeds or nuts, or atreatment of performing washing and sterilization when they areprocessed as food, are also increased.

Particularly, for vegetables to be eaten raw, such as salad vegetables,washing is performed and a sterilization treatment is performed in orderto prevent a change in quality or decomposition until they are eaten.For this, there is also a method in which a washing step by clean waterand a sterilization step using a chemical agent are independentlyperformed in separate work places. However, recently, as a rationalmethod in which such washing and sterilization are performed at the sametime, a method of using ozonized water is proposed. As this method,there is a revolving current method disclosed in Japanese PatentLaid-Open No. 19376/1997. That is, this is a method in which storedwater in a washing tank into which vegetables are put is circulated by acirculation pump to generate a revolving current in the washing tank,and an ozone-containing gas generated by an ozone generator is blowninto the washing tank. By this, bacteria stuck on the vegetables aresterilized, and at the same time, pollutants such as agriculturalchemicals are also removed, and moisture is supplied to cells of thevegetables to revive freshness. As another method, there is a methoddisclosed in Japanese Patent Laid-Open No. 290049/1999. In this method,after vegetables are received in a space of a sealed type chamber, lowconcentration ozonized water is poured to such a degree that thevegetables are not soaked. Stored ozonized water is circulated andjetted to the vegetables. By this, washing and sterilization of thevegetables are performed under a mixture atmosphere of gaseous ozone andozonized water.

In the conventional methods, first, in the revolving current methoddisclosed in Japanese Patent Laid-Open No. 19376/1997, even if aircontaining ozone is blown into the washing tank, before the ozonedissolves, most of it passes through the washing tank without stoppingand is diffused into the atmosphere. Thus, there has been a problem in asterilization effect by ozone.

On the other hand, in the method disclosed in Japanese Patent Laid-OpenNo. 290049/1999, the ozonized water is water stored in the sealedcontainer, and this stored water is cyclically used as wash water. Ascompared with the former, although an improvement in the sterilizationeffect by ozone can be expected, gradual contamination of the wash watercan not be avoided. Thus, after washing by the ozonized water, it isnecessary to perform a step of, for example, performing washing by clearwater such as tap water,

Further, since both are of a batch type in which vegetables are put intothe container and are washed, they are unsuitable methods as acontinuous method applied to an apparatus for continuously washingplenty of vegetables.

In view of such circumstances, the invention has an object to provide amethod in which a large amount of food materials can be alwayscontinuously washed and sterilized by fresh ozonized water, and whichuses a small quantity of water and is economical.

DISCLOSURE OF THE INVENTION

The invention has been made in view of the above, and a washingapparatus of the invention comprises an ozonized water generator, acylindrical washing tank in which food materials are put and which canrotate to wash the food materials, a drainage part formed at a part ofthe washing tank and including a large number of openings to such adegree that water passes through and the food materials do not passthrough, and a wash water piping which is inserted and disposed in thewashing tank in an axial direction and in which a water spray hole forspraying wash water including at least ozonized water generated by theozonized water generator into the washing tank is formed, and ischaracterized in that while at least part of the wash water sprayed fromthe wash water piping is drained from the washing tank every rotation ofthe washing tank, washing of the food materials is performed.

Besides, the above apparatus is provided with a receiving tank for thewash water drained from the washing tank and a wash water return currentpiping for returning at least one part of the wash water in thereceiving tank to an inlet side of the ozonized water generator. Bythis, at least the part of the wash water drained from the washing tankis returned to the materials water inlet side of the ozonized watergenerator and is cyclically used, so that water consumption can begreatly reduced.

Besides, an inlet for the food materials is formed at one end of thewashing tank, a drain port is formed at the other end, and a spiralmember is formed inside the washing tank. By this, the food materialsput in the washing tank can be washed while they are conveyed to thedrain port from a side of the inlet with the rotation of the washingtank, and a continuous massive treatment of food materials becomes easy.Incidentally, as the spiral member, there are a continuous one and adiscontinuous one, and both can be adopted.

Besides, it is preferable that the drainage part of the washing tank isformed to be continuous in a longitudinal direction of the washing tank,and by this, it becomes possible to renew all of the wash water everyrotation. Besides, in order to facilitate drainage from the drainagepart, it is preferable to form the drainage part out of a wire net or aporous metal plate. Further, in order to facilitate the transfer of thefood materials in the washing tank, it is preferable to obliquelydispose the washing tank so that a falling gradient is realized from theside of the inlet to the side of the drain port. Incidentally, it isalso possible to reduce the amount of wash water supply by forming thedrainage part intermittently in the longitudinal direction of thewashing tank and by forming a draining portion and a staying portion.

Besides, it is preferable that a sectional shape of the washing tank isa circle, an ellipse, or a polygonal, and especially a regular hexagonis optimum in that manufacture is easy and a suitable depth of thestaying wash water can be secured.

Further, in a preferable embodiment, the wash water piping is maderotatable, and by this, a water spray angle of the wash water piping ismade variable in accordance with the size, shape and the like of thefood materials.

Besides, a method is also effective in which the washing tank isconstructed so that normal and reverse rotations can be made, and it issuitably rotated normally or reversely in a state where the wash wateris stored in the inside, so that the washing effect of food materials israised by a swing action of the washing tank, and the amount of washwater used is reduced.

Besides, the wash water piping is constituted by a first wash waterpiping including a water spray hole in a front half portion of thewashing tank and a second wash water piping including a water spray holein a rear half portion, and one of ozonized water and clean water isenabled to flow to both the wash water pipings by a changeover operationof valves. Especially, a preferable method is a method in which as theozonized water generator, an electrolytic ozonized water generator isadopted in which ozonized water is generated at an anode side byelectrolysis of water, and alkaline water is generated at a cathodeside, and the ozonized water or the alkaline water, or clean water isenabled to flow to both the wash water pipings by the changeoveroperation of the valves. In this case, it becomes possible to use thealkaline water for the degreasing washing of the food materials or thedegreasing washing of the washing tank itself.

Besides, the receiving tank for the drain wash water is constituted by afront receiving tank for wash water drained from the front half portionof the washing tank, and a rear receiving tank for wash water drainedfrom the rear half portion. Then, at least one part of the drain washwater in the rear receiving tank is enabled to be supplied to an inletside of the first wash water piping. By this, it becomes possible toreuse the ozonized water used in the rear half portion in the front halfportion.

Further, a method in which at least one part of the drain wash water inthe rear receiving tank is returned to the inlet side of the ozonizedwater generator, or a method in which at least one part of the drainwash water in the front receiving tank is returned to the inlet side ofthe ozonized water generator is also a preferable method which isexpected to have a great effect in reduction of the amount of cleanwater used for the washing of the food materials.

Incidentally, an ozonized water tank for storing the ozonized watergenerated by the ozonized water generator is provided, and the secondwash water piping (ozonized water piping) is connected to both theozonized water tank and the ozonized water generator, and when supply ofthe ozonized water from both is enabled, a flexible change can be madein the amount of ozonized water supply in accordance with a change ofthe amount of ozonized water demanded.

Besides, it is preferable that the washing tank has a structure thatunit cylindrical bodies in each of which a spiral member is formed alongan inner wall are coupled to each other so as to be separable. By this,the disassembly and washing of the washing tank is simplified.

Next, a food materials washing method using the above washing apparatusis characterized in that food materials are put in from an inletdisposed at one end of a cylindrical washing tank, the food materialsare drained from a drain port formed at the other end of the washingtank by rotating the washing tank, ozonized water is sprayed from a washwater piping disposed in the washing tank in an axial direction, thesprayed ozonized water is drained by rotation of the washing tankthrough a drainage part formed in the washing tank and including anopening to such a degree that water passes through and the foodmaterials do not pass through, whereby while at least one part of theozonized water sprayed from the wash water piping is drained from thedrainage part of the washing tank every rotation of the washing tank,washing and transfer of the food materials are performed.

Besides, there is also a method in which at least one part of theozonized water drained from the washing tank is returned to a materialswater inlet side of the ozonized water generator, and the drainedozonized water is cyclically used, so that water consumption can begreatly reduced.

Also in these methods, a first wash water piping having a water sprayhole in a front half portion of the washing tank and a second wash waterpiping having a water spray hole in a rear half portion are used as thewash water piping. Then, as set forth above, it is also a preferablemethod to spray the drain wash water, which was sprayed to the rear halfportion of the washing tank and drained from the second wash waterpiping, to the front half portion of the washing tank through the firstwash water piping, or to return the drain ozonized water drained fromthe front half portion to the materials water inlet side of the ozonizedwater generator. Besides, the ozonized water is ozonized water generatedat an anode side by an electrolysis method of water. It is also apreferable mode that one of the ozonized water, alkaline water generatedat a cathode side by the electrolysis method, and clean water is enabledto flow to the first wash water piping and the second wash water pipingby a changeover operation of valves.

Especially, in the case where the electrolytic ozonized water generatoris used, it becomes possible to adopt a washing method includingfollowing processes by changing over and using the ozonized water, thealkaline water, and the clean water.

A process: “washing tank before-washing process” in which while thealkaline water generated at the cathode side by the electrolysis methodor the clean water is sprayed from one of or both of the first and thesecond wash water pipings, before-washing of the washing tank itself isperformed.

B process: “food materials washing process” in which the food materialsare put in from the inlet while the washing tank is rotated, and waterspray of the ozonized water is performed from at least the second washwater piping, so that while at least one part of the sprayed ozonizedwater is drained every rotation of the washing tank, the food materialsare conveyed in the washing tank, and washing and sterilization of thefood materials are performed.

C process: “after-washing process of washing tank” in which aftercompletion of the food materials washing process, while the alkalinewater or the clean water is sprayed from one of or both of the first andthe second wash water pipings, after-washing of the washing tank itselfis performed.

Besides, as the A process, it is preferable to select a processincluding at least one of following A1 step to A3 step.

A1 step: “washing tank alkaline water before-washing step” in which thealkaline water is supplied to both the first and the second wash waterpipings to perform alkaline water washing of the washing tank.

A2 step: “washing tank water before-washing step” in which the cleanwater is supplied to both the first and the second wash water pipings toperform water washing of the washing tank.

A3 step: “washing tank alkaline water and water before-washing step” inwhich the A2 step is performed after the A1 step is performed.

Besides, as the B process, it is preferable to select a processincluding at least one of following B1 step to B3 step.

B1 step: “food materials before-washing and washing step” in which theclean water is sprayed from the first wash water piping in the fronthalf portion of the washing tank, and the ozonized water is sprayed fromthe second wash water piping in the rear half portion of the washingtank.

B2 step: “food materials degreasing and washing step” in which thealkaline water is sprayed from the first wash water piping in the fronthalf portion of the washing tank.

B3 step: “food materials ozonized water washing step” in which theozonized water is sprayed from the second wash water piping into therear half portion of the washing tank, and the ozonized water is sprayedfrom the first wash water piping into the front half portion as well.

Besides, as the C process, it is preferable to select at least one offollowing C1 step to C3 step.

C1 step: “alkaline water after-washing step of washing tank” in whichthe alkaline water is supplied to both the first and the second washwater pipings to perform alkaline water washing of the washing tank.

C2 step: “water after-washing step of washing tank” in which the cleanwater is supplied to both the first and the second wash water pipings toperform water washing of the washing tank.

C3 step: “Alkaline water and water after-washing step of washing tank”in which the C2 step is performed after the C1 step is performed.

Incidentally, as a reuse method of the wash water, there is “ozonizedwater recycling” in which in the B3 step, the drain ozonized waterdrained from the rear half portion of the washing tank is supplied tothe first wash water piping and is sprayed from the first wash waterpiping to the front half portion of the washing tank, or “wash waterreturn method” in which at least one part of the drain wash water fromthe washing tank in any one of the A process to the C process isreturned to the materials water inlet port of the ozonized watergenerator.

Besides, also in these methods, in a state where the wash water sprayedinto the washing tank is stayed, a rotation direction changeoveroperation is performed at least one time in which a rotation directionof the washing tank is reversed and is next normally rotated, so that astaying time is prolonged, a water level of the wash water is made deep,And a contact time between the food materials and the wash water isprolonged, and whereby efficiency of washing and sterilization of thefood materials can be improved and the amount of wash water used can bereduced by the effective use of the wash water. Incidentally, it ispreferable that the rotation speed is adjusted so that the rotationspeed of the washing tank at the time of the swing operation becomesfaster than the rotation speed at the time of non-swing.

Further, it is also a preferable method that the spiral member isdisposed in the washing tank to perform transfer of the food materialssmoothly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view showing an embodiment of a food materials washingapparatus according to the invention.

FIG. 2 is a plan view of FIG. 1.

FIG. 3 is a main part sectional view of a washing tank of FIG. 1, FIG.3( a) is a sectional view of a washing tank front half portion, and FIG.3( b) is a sectional view of a rear half portion.

FIG. 4 is a conceptual view showing a washing process of food materialsby the washing apparatus of FIG. 1.

FIG. 5 is a process view showing temporal changes of staying and drainof ozonized water in a washing tank of FIG. 1.

FIG. 6 is a main part sectional view showing an example of a washingtank having an elliptical section according-to the invention, FIG. 6( a)shows a state in which a major axis direction is vertical, and FIG. 6(b) shows a state in which it is horizontal.

FIG. 7 is a main part schematic view of an electrolytic ozonized watergenerator used in the invention.

FIG. 8 is a flow view of a washing apparatus of the invention in whichan electrolytic ozonized water generator is applied.

FIG. 9 is a changeover conceptual view of a washing process by theapparatus of FIG. 8.

BEST MODE FOR CARRYING OUT THE INVENTION Outline of Washing Apparatus

Hereinafter, the present invention will be described in detail withreference to the drawings. FIG. 1 is a side view showing a foodmaterials washing apparatus according to the invention, FIG. 2 is itsplan view, FIG. 3 is a sectional view of a washing tank shown in FIGS. 1and 2, FIG. 3( a) is a sectional view of a front half portion, and FIG.3( b) is a sectional view of a rear half portion.

In these drawings, a sectional shape of a washing tank i is a regularhexagon as shown in FIG. 3( a) and FIG. 3( b). A drainage part 4 isprovided at one side of six sides. A large number of openings aredisposed in this drainage part 4. The openings have such a degree ofsize that food materials do not pass through and water passes through.The drainage part 4 is formed of a wire net, a porous plate or the likedisposed in a longitudinal direction of the washing tank 1.After-mentioned spiral members 3 are disposed along the inner surface inthe washing tank 1.

Besides, a double pipe 14 is disposed substantially at the center of afront half portion of the washing tank 1 in an axial direction. Thedouble pipe 14 is formed of an inner pipe as a second wash water piping2 and an outer pipe as a first wash water piping 9. The second washwater piping 2 is disposed over the whole length of the washing tank 1in the axial direction. The first wash water outer pipe 9 is formed onlyin the front half portion of the washing tank 1. Besides, water sprayholes 2 a are formed only in a portion of the second wash water piping 2corresponding to the rear half portion of the washing tank 1. Waterspray holes 9 a are formed only in a portion of the first wash waterpiping 9 corresponding to the front half portion of the washing tank.

The washing tank 1 used in the invention is a long cylinder formed bycoupling unit cylinders 1 a, 1 a, . . . to be separable at coupled faces1 b, 1 b, . . . The spiral members are formed along the inner walls ofthe unit cylinders 1 a, 1 a, . . . This is based on such considerationthat the unit cylinders can be divided and immersed in hot water in thecase where heat sterilization of the washing tank 1 under obligation byfood sanitation law is performed. An inlet 5 for food materials isformed at an input side of the washing tank 1, and an outlet 6 is formedat output side. A receiving basket 7 formed of a wire net or the like isdisposed below the outlet 6 as a receptacle for the food materialsoutput. Besides, the second and the first wash water pipings 2 and 9 aredisposed at the center of the inside of the washing tank 1 to passthrough in the longitudinal direction. Incidentally, the washing tank 1is rotatably held through a not-shown bearing member with respect to thesecond and the first wash water pipings 2 and 9. Besides, both end partsof the through pipings are rotatably supported to support members 20 aand 20 c by bearing members 21 a and 21 b. The support members 20 a and20 c are provided upright on a base B. Besides, the beating members 21 aand 21 b are respectively held to the support members 20 a and 20 crotatably in the up-and-down direction. Two support members 20 b and 20c at the side of the inlet 5 of the washing tank 1 can be respectivelyextended or contracted in the up-and-down direction. By this, it isobliquely disposed so that the portion on the side of the food materialsinlet 5 of the washing tank 1 is high and the portion on the side of theoutlet 6 is low. Incidentally, the support member 20 b is a member forholding the food materials inlet 5 from below. The support member 20 band the food materials inlet 5 are rotatably coupled through a bracket(not shown) or the like. Incidentally, the inlet 5 portion is a bodyseparatable from the washing tank 1. An end of the inlet 5 portion isfitted into a tip opening of the washing tank 1 and is disposed.

Besides, a ring member 24 is disposed around the outer peripheralsurface of a body of the washing tank 1. The washing tank 1 can berotated by a belt 23 stretched between the ring member 24 and a drivemotor 22. Incidentally, reference numeral 8 in the drawing denotes areceiving tank for drain wash water disposed just under the washing tank1. This is for temporarily storing the wash water drained from thedrainage part 4 of the washing tank 1. There is a case where the washwater in the receiving tank is cyclically used as described later.

Next, FIG. 4 is a drawing conceptually showing a transfer process offood materials by the rotation of the washing tank 1, which is one ofthe features of the invention. FIG. 4 (a) shows a state where foodmaterials A are put in the washing tank 1 from the food materials inlet.The put food materials A are sequentially sent to the side of the outlet6 by the spiral members 3 as shown in FIGS. 4( b) and 4(c). Then, thefood materials A drop downward from the outlet 6 then are output. Thespiral members 3 are disposed along the inner wall of the washing tank1. Accordingly, the food materials A are sent from the inlet side to theoutlet side by the rotation of the washing tank 1 and by the spiralmembers 3. Thus, it is not necessarily indispensable to obliquelydispose the washing tank 1 with a falling gradient from the inlet sideto the outlet side as shown in FIG. 1.

Washing Tank and Washing Method

Next, FIG. 5 is a process view of the embodiment of the invention. FIG.5 shows a state of storage and drain of the wash water (ozonized water)by the rotation of the washing tank 1, which is another feature of theinvention. In the drawing, one side of the washing tank 1 indicated bydouble lines denotes the drainage part 4 formed of the above-mentionedwire net or the like. In Step 1 of the drawing, the washing tank 1 isrotated in a clockwise direction as indicated by an arrow (X). Theozonized water is always sprayed from the water spray hole 2 a of thewash water piping (the drawing shows the second wash water piping 2).The washing tank 1 is rotated from this state, and when a state occursin which one apex of the hexagon is positioned down as shown in Step 2,the ozonized water W which has been sprayed up to that time is collectedin the apex part and its depth increases. However, further, as shown inStep 3, when one side of the hexagon is positioned down, the ozonizedwater W comes to have an inverted trapezoid shape with the one side asthe bottom, and the depth becomes shallow. In the process of therotation of the washing tank 1, the food materials (not shown) areraised upward according to the rotation of the washing tank 1 and dropas indicated by an arrow (Y) in the drawing. The food materials repeatsuch movement. Thus, all surfaces of the food materials are apt toreceive the water spray of fresh ozonized water. Similarly, when therotation of the washing tank 1 proceeds from Step 4 to Step 7 in thedrawing, ozonized water sprayed in this process is graduallyaccumulated. The depth gradually becomes deep. At the same time, it isgradually contaminated by the washing of the food materials.

Next, when a state of Step 8 in the drawing occurs, the ozonized water Wstored in the washing tank 1 comes in contact with the drainage part 4of the washing tank 1. From this point of time, drainage of the storedozonized water W from the drainage part 4 is started. Between Step 9 andstep 12 in the drawing, since the drainage part 4 is positioned down,the sprayed ozonized water is also drained, and the storage of theozonized water does not occur. However, at the same time, this step is astep in which the surface of the food materials on which thecontaminated ozonized water is stuck is washed by fresh ozonized waterand the ozonized water is drained. Next, Steps 13 to 16 show a processfor washing the food materials while the ozonized water W is againstored in the washing tank 1.

As stated above, in this embodiment, replacement of ozonized water isperformed every rotation of the washing tank 1. As a result, thefollowing effects are obtained. In the state where the drainage part 4is positioned down, when the ozonized water which has been stored up tothat time and is contaminated by the washing of the food materials isdrained, and at the same time, by the constantly sprayed ozonized water,the surface of the food materials on which the contaminated ozonizedwater is stuck is washed by the fresh ozonized water.

Incidentally, it is preferable that a water spray angle of the ozonizedwater is adjustable. Since the water spray angle of the ozonized wateris determined by the formation position of the water spray holes 2 a ofthe wash water piping 2, the wash water piping 2 is made rotatable inorder to make the water spray angle variable. By this, while a positionin the washing tank 1 to which water should be sprayed is checked inaccordance with the kind, size or input amount of food materials, itbecomes possible to adjust the water spray angle by rotating the washwater piping 2.

The above description relates to an example of a case where the washingtank 1 is rotated in only one direction. In FIG. 5, the states of Step 1to Step 5 show the process in which the washing tank 1 is rotated by120° so that the drainage part 4 is moved from the upper left positionto the upper right position. During this, although the ozonized water isstored, it is not drained. Then, when the state of the Step 1 reachesthe state of Step 5, the rotation direction of the washing tank 1 ischanged over from the normal rotation to the reverse rotation, and thereverse rotation is performed like Step 5→step 4 . . .→Step 1. Then,when the state again reaches the state of Step 1, the rotation directionis again returned to the normal rotation, and the rotation is performedfrom Step 1 to Step 5. As stated above, it is also possible to performthe washing while the storage amount of the ozonized water W isincreased. In the reverse rotation step of the washing tank 1, the foodmaterials and the ozonized water are swung by swinging the washing tank1, the ozonized water covering the surfaces of the food materials isrenewed, and the washing sterilization effect is raised. Therefore, itis preferable to provide the reverse rotation step of the washing tank1.

Incidentally, the number of times of normal and reverse rotations of thewashing tank 1, the swing angle, and the rotation speed at the time ofthe swing are arbitrarily selected. It is preferable that the number ofswings is roughly not less than one and not larger than three. If largerthan this, there is a fear that a harmful effect of a drop in throughputbecomes more serious than an increase in washing effect. Besides, it ispreferable that the swing angle is approximately not less than 100° andnot higher than 150°, and is especially approximately 120°. Further, therotation speed of the washing tank 1 at the time of the swing may be thesame as the normal rotation speed. However, in order to raise thewashing effect by swinging the inner ozonized water and food materials,it is preferable to make the rotation speed higher than the normalrotation speed, By the existence of the changeover operation of therotation direction and by suitably setting the number of times ofchangeover and the rotation speed at the time of the swing, it becomespossible to adjust a contact time in relation to the ozonized water andto adjust the depth of the ozonized water stayed in the washing tank inaccordance with the amount and size of the food materials. By this,wasteful spray of the ozonized water is prevented, and the amount ofozonized water strayed can be adjusted to an optimum state.

Besides, although the foregoing embodiment shows that the shape of thewashing tank 1 is a regular hexagon in section, another shape may beadopted. FIG. 6 shows an example of a case where the section iselliptical. The same drawing (a) shows a state where the washing tank 1is rotated aid a major diameter direction d1 of an ellipse is positionedin the vertical direction, and the same drawing (b) shows a state wherea minor diameter direction d2 of the ellipse is positioned in thevertical direction. As is apparent from these drawings, the depth h ofthe stayed ozonized water W is different between the case (a) where themajor diameter method d1 is in the vertical position and the case (b)where it is in the horizontal position. In the case (a) where the majordiameter method d1 is in the vertical position, a water depth h1 becomesdeep, and in the case where the minor diameter method d2 is in thevertical position, a water depth h2 becomes shallow. Accordingly, in thestate of the same drawing (a), the food materials are immersed in theozonized water deeply and narrowly, and in the state of the same drawing(b), they are immersed in the ozonized water shallowly and widely. Bythis repetition, all the food materials are uniformly washed.Incidentally, the swing operation may be performed in either of thestate of the same drawing (a) and the state of the same drawing (b).However, in the case where the swing operation is performed in the stateof the same drawing (a), the drainage part 4 must be provided at theposition shown in the same drawing (a). In the case where the swingoperation is performed in the state of the same drawing (b), thedrainage part 4 must be provided at the position shown in the samedrawing (b).

The sectional shape of the washing tank 1 may be, in addition to theforegoing regular hexagon and the ellipse, a circle or a polygonal shapesuch as a regular triangle, a square, a rectangle, or a regular octagon.However, from the viewpoint of ease of manufacture and ease ofrealization of a suitable water depth, it is preferable that the sectionis the ellipse in addition to the regular hexagon.

Next, with respect to the drainage part 4, in the foregoing embodiment,a porous member such as a wire net is disposed on the whole of onesurface of the hexagonal cylinder in the longitudinal direction of thewashing tank. However, with respect to the drainage part 4, there arevarious modified examples. For example, the drainage part 4 isintermittently formed on one surface of the hexagonal cylinder in thelongitudinal direction of the washing tank. The drainage parts 4 areformed like stepping-stones with suitable spaces on the respectivesurfaces of the hexagonal cylinder, In the former case, in the sectionwhere the drainage part is formed, drainage of the ozonized water isperformed by one rotation of the washing tank. However, in the sectionwhere the drainage part is not formed, the drainage of the ozonizedwater is not performed. Flowing of the ozonized water occurs from thesection having no drainage part to the section having the drainage part.Washing of the food materials is continued through the decrease of theozonized water by this flowing and newly sprayed ozonized water. On theother hand, in the latter case, since the drainage parts areintermittently formed on the respective surfaces of the hexagon, thedrainage of the ozonized water is performed at any rotation angle. As aresult, flowing of the ozonized water occurs from the section where thedrainage part is positioned upper toward the section where the drainagepart is positioned lower then drainage of the ozonized water isperformed, and at the same time, supply of new ozonized water by sprayof ozonized water is also performed. Thus, washing of the food materialsis continued by mixture water of the stayed ozonized water and the newozonized water. In any of these methods, in an arbitrary section of thewashing tank 1, the respective Steps of FIG. 5 are carried out, andthere is no problem in the washing effect. However, from the viewpointof manufacture of the washing tank, it is preferable to form acontinuous drainage part on one specified surface of the washing tank 1.

Electrolytic Ozonized Water Generator

Next, as the ozonized water generator used in the invention, forexample, an apparatus in which an ozone gas is dissolved in water togenerate the ozonized water can be adopted. However, as described later,in view of the merits that secondarily generated alkaline water can beused and high concentration ozonized water can be obtained in a shorttime, an ozonized water generator using an electrolysis method of wateris preferable.

As such an electrolytic ozonized water generator, there is a well-knownapparatus as disclosed in Japanese Patent Laid-Open No. 134677/1996.FIG. 7 shows its outline. In FIG. 7, an anode electrode 32 is disposedon one surface of an organic solid electrolyte film 31 so as to put theanode electrode 32 and the electrolyte film 31 together. Similarly, acathode electrode 33 is disposed on the other surface of the organicsolid electrolyte film 31 so as to put the cathode electrode 33 and theelectrolyte film 31 together. As the organic solid electrolyte film 31,a fluorine-based ion exchange membrane with ozone resistance, or thelike can be named. The anode electrode 32 is made of a wire net of noblemetal having an ozone generation catalytic function. Then, lath nets 34and 35 are disposed on the outside surfaces of both the electrodes 32and 33 over the whole length. The lath nets 34 and 35 are respectivelylath nets made of metal having corrosion resistance against ozone, suchas titanium or stainless steel. The respective electrodes are connectedto a direct current power source (not shown) so that a direct currentvoltage can be applied between both the electrodes. Besides, an anodeside jacket 39 and a cathode side jacket 40 are respectively disposedoutside so as to contain the respective electrodes 32 and 33 and thelath nets 34 and 35. An inflow port 41 for materials water on the anodeside, an inflow port 42 for a materials water on the cathode side, anoutflow port 43 for the ozonized water and an outflow port 44 for thealkaline water are respectively formed in the respective jackets.

In this apparatus, while the direct current voltage is applied betweenboth the electrodes, materials water is supplied to the respectiveelectrode sides from a materials water piping 30 through valves 36 and37 and the respective inflow ports 41 and 42 for materials water, thenelectrolysis of water is performed. When the electrolysis of water isperformed, an OH ion (OH⁻) generated by the electrolysis of water iscollected at the side of the anode 32. This OH ion becomes ozone by theaction of the ozone generation catalysis of the anode. The ozone isimmediately dissolved into the water and the ozonized water isgenerated. This ozonized water is fed into an ozonized water tank (notshown) from the outflow port 43 for ozonized water through a piping 38.Here, a complicated flow path is formed in the vicinity of the outersurface of the anode electrode 32 by the lath net 34 which is made ofwire nets mutually connected in a stagger shape.

Thus, many small vortex flows are formed on the outer surface of theanode electrode. The ozone generated on the electrode surface is caughtin the vortex flows and is quickly dissolved in the water. As a result,an amount of ozone gas flowing out together with water is decreased.Then, an amount of the dissolved ozone is increased, and highconcentration ozonized water of approximately 30 ppm can be obtained.

Similarly, a hydrogen ion (H⁺) generated by the electrolysis of water iscollected to the electrode surface at the side of the cathode electrode33. Then, the hydrogen ion becomes hydrogen gas, and is released fromthe water. An alkali metal ion, such as a sodium ion (Na⁺) or calciumion (Ca⁺⁺), and an alkaline earth metal ion, which are contained in thewater in extremely small quantities, are also collected to the cathodesurface. Those are condensed and the water at the cathode side is madealkaline water. Together with the foregoing hydrogen gas, it is fed toan alkaline water tank (not shown) from the outflow port 44 for alkalinewater through a piping 45. As stated above, the alkali metal ion and thealkaline earth metal ion (mainly Na⁺) contained in the water inextremely small quantities together with the hydrogen gas, are alsocondensed at the cathode side. As a result, it is confirmed thatalkaline water of not less than pH 9 and not higher than pH 11 or notless than that is generated as water at the cathode side.

Incidentally, this pH value varies according to the ratio of thequantities of water supplied to both the electrode sides. If thequantity of water supplied to the cathode side is made smaller than thequantity of water supplied to the anode side, the pH value becomesrelatively high, on the contrary, if made larger, the pH value becomeslow.

Next, a food materials washing apparatus according to the inventionusing the electrolytic ozonized water generator and a washing methodwill be described. FIG. 8 is a whole flow view of the food materialswashing apparatus of the invention, and FIG. 9 is an enlarged view ofthe washing tank 1 and the double pipe 14 shown in FIG. 8. Clean watersuch as tap water supplied from a piping 51 branches off to a piping 51a and a piping 51 b. The piping 51 a is a piping leading to anelectrolytic ozonized water generator 10 (hereinafter simply referred toas “ozonized water generator”). The piping 51 b is a piping leading to awashing system. Materials water supplied from the piping 51 a becomessoft water in a water softener 11 in which a calcium ion (Ca⁺⁺) and amagnesium ion (Mg⁺⁺) contained in the materials water are removed, Thesoft water is supplied through the piping 30 to the ozonized watergenerator 10. Then, here, as described before, it is subjected to anelectrolysis treatment, and ozonized water and alkaline water aregenerated. The ozonized water is fed to an ozonized water tank 12through pipings 38 and 52 b. The alkaline water is fed to an alkalinewater tank 13 through the piping 45.

Washing Process of a Washing Tank and Food Materials

In an actual washing operation of food materials, the following processis carried out: “Before-washing process of washing tank” (A process) inwhich washing of the washing tank itself is performed before washing ofthe food materials; “Food materials washing process” (B process) carriedout subsequently to the washing of the washing tank 1; and“After-washing process of washing tank” (C process) in which the washingtank contaminated by the washing of the food materials is washed.

Before-washing Process of Washing Tank

There are following steps as the above “Before-washing process ofwashing tank” (A process). “Alkali before-washing step of washing tank”(A1 step) in which washing of the washing tank is performed by alkalinewater; “water before-washing step of washing tank” (A2 step) in whichwashing of the washing tank is performed by clean water; and “Alkalinewater and water before-washing step of washing tank” (A3 step) in whichclean water washing is performed after alkaline water washing.

“Alkali Before-washing Step of Washing Tank”

First, in the above A1 step (Alkali before-washing step of washingtank), an oily substance stuck on the washing tank 1 is dissolved andremoved by the alkaline water. In this step, valves V1, V3 and V6 areset “closed”, valves V2, V4 and V5 are set “opened”, and a pump P1 isactivated. Then, the alkaline water in the alkaline water tank 13 issupplied to a piping 55 through a piping 54, the pump P1, and the valveV2. In that portion, the alkaline water is divided into two flows, oneleading to the second wash water piping 2 through a piping 61, the valveV5 and a piping 56, and the other leading to the first wash water piping9 from the valve V4 through, pipings 57 and 62. The first wash waterpiping 9 constitutes the double pipe 14 as an outer pipe part of thesecond wash water piping 2. The outer pipe part exists from an end atthe side of the food inlet 5 of the washing tank 1 to a substantiallyhalf position of the washing tank 1 in the axial direction, that is, ina former half portion U of the washing tank 1 in the axial direction.Besides, many wash water spray holes 9 a are bored in the axialdirection. On the other hand, the second wash water piping 2 as an innerpipe part of the structure of the double pipe 14 extends over the wholelength T of the washing tank 1. Its water spray holes 2 a are formed ina portion where the first wash water piping 9 does not exist, that is,only in a rear half portion D of the washing tank 1.

Thus, the alkaline water supplied from the piping 62 to the first washwater piping 9 is sprayed to the front half portion U of the washingtank 1 and performs washing of the washing tank. On the other hand,since the water spray holes 2 a are included in only the rear halfportion D of the washing tank 1, the alkaline water supplied through thepiping 56 to the second wash water piping 2 (inner pipe of the doublepipe 14) performs washing of only the rear half portion D of the washingtank 1.

Also in this washing process, the washing tank 1 is rotated in theforegoing manner. Accordingly, the alkaline water repeats the washingtank storage process, the washing process, and the drain process in thisorder every rotation of the washing tank. Incidentally, in this washingstep, it is also possible to perform the swing operation by changingover the rotation direction of the washing tank between the normal andreverse directions. However, there is no problem even if the swingoperation is not performed.

Water Before-washing Step of Washing Tank

Next, the A2 step is a washing step using the clean water instead of thealkaline water, and is a step for washing away dust stuck on the washingtank 1. In this A2 step, the pump P1 is stopped, the valves V1, V2 andV6 are set “closed”, and the valves V3, V4 and V5 are set “opened”. Theclean water is supplied to the branch piping 51 b branching off from theclean water piping 51. The clean water is divided into two flows throughthe valve V3. Part of the clean water is supplied through the pipings 57and 62 to the first wash water piping 9. The remainder of the cleanwater enters the piping 61 through the valve V4, and then, is suppliedto the second wash water piping 2 through the valve V5 and the piping56. Then, similarly to the foregoing case, in the front half portion Uof the washing tank 1, the clean water is sprayed from the first washwater piping 9. In the rear half portion D of the washing tank 1, theclean water is sprayed from the second wash water piping 2, and thewater washing in the washing tank is performed while the washing tank 1is rotated.

Alkaline Water and Water Before-washing Step of Washing Tank

In the A3 step (alkaline water and water before-washing step of washingtank), after the washing by the alkaline water of the A1 step isperformed, water washing by the clean water of the A2 step is againperformed. With respect to this step, the propriety of its executionshould be suitably judged according to the kind of food materials to bewashed, pH of the alkaline water used, and the like.

Food Materials Washing Process

When the washing prior to the use of the washing tank 1 is ended in thisway, the procedure proceeds to the [Food materials washing process] (Bprocess). In the [Food materials washing process] (B process), whilepredetermined food materials are put in the washing tank 1 through theinlet 5, washing of the food materials by ozonized water is performed.Further, there are the following steps as the B process : “Pre-washingand washing step of food materials” (B1 step) in which food materialsare washed by clean water and ozonized water; “Degreasing and washingstep of food materials” (B2 step) in which washing is performed usingalkaline water and ozonized water; and “Ozonized water washing step offood materials” (B3 step) in which washing is performed by using onlyozonized water.

Pre-washing and Washing Step of Food Materials

First, the B1 step (Pre-washing and washing step of food materials) iswashing by a combination of clean water and ozonized water. This step isadopted in such a case that dirt such as soil or dust is stuck on thefood materials. While the washing tank 1 is rotated, soil or dirt stuckon the food materials is removed by the washing using the clean water inthe front half portion U as the upstream side of the washing tank 1.Subsequently, finish washing and sterilization by the ozonized water isperformed in the rear half portion D of the washing tank 1 as thedownstream side. Accordingly, in this step, for the first wash waterpiping 9 for supplying the clean water, the valve V3 is set “opened”,and the valve V4 is set “closed”. The clean water is supplied from thepiping 51 b of the clean water through the valve V3 and the pipings 57and 62 to the first wash water piping 9. The clean water is sprayed tothe front half portion U in the washing tank 1, and the water washing ofthe food materials is performed. On the other hand, for the second washwater piping 2 for supplying the ozonized water, the valves V1 and V5are set “closed”, the valve V6 is set “opened”, and a pump P2 isactivated. Then, the ozonized water is supplied from the ozonized watertank 12 through a piping 58, the pump P2, a piping 59, the valve V6, andthe pipings 59 b and 56 into the second wash water piping 2. Theozonized water is sprayed to the rear half portion D of the washing tank1, and the finish washing and sterilization of the food materials areperformed.

Incidentally, also in this case, in order to raise the washingefficiency, the swing operation for suitably repeating the normalrotation and reverse rotation of the washing tank 1 in the state wherethe clean water or the ozonized water is stayed in the washing tank 1may be performed.

Food Materials Degreasing and Washing Step

Next, the B2 step (food materials degreasing and washing step) iswashing by a combination of alkaline water and ozonized water. It isadopted in such a case that dirt due to an oily substance is stuck onthe food materials. While the washing tank 1 is rotated, the dirt due tothe oily substance stuck on the food materials is removed by the washingusing the alkaline water in the former half portion U as the upstreamside of the washing tank 1. Subsequently, finish washing andsterilization by the ozonized water is performed in the rear halfportion D of the washing tank 1 as the downstream side. Accordingly, inthis step, for the first wash water piping 9 for supplying the alkalinewater, similarly to the foregoing case of the alkaline water supply, thevalves V2 and V4 are set “opened”, the valves V1, V3 and V5 are set“closed”, and the pump P1 is activated. Then, the alkaline water in thealkaline water tank 13 is supplied through the piping 54, the pump P1,the valve V2, the piping 55, the valve V4, and the pipings 57 and 62into the first washing piping 9. Then, the alkaline water is sprayedfrom the water spray holes formed in the first wash water piping 9 tothe front half portion U of the washing tank 1, and dissolving andwashing of the oil substance stuck on the food materials is performed.On the other hand, similarly to the above first step, the ozonized waterin the ozonized water tank 12 is supplied through the piping 58, thepump P2, the piping 59, the valve V6, and pipings 59 b and 56 into thesecond wash water piping 2. Then, the ozonized water is sprayed to therear half portion D of the washing tank 1. By this, the finish washingand sterilization by the ozonized water is performed for the foodmaterials sent from the front half portion U of the upstream side.

Incidentally, also in this case, in order to raise the washingefficiency, the swing operation for suitably repeating the normalrotation and reverse rotation of the washing tank 1 in the state wherethe alkaline water or the ozonized water is stayed in the washing tank 1may be performed.

Food Materials Ozonized Water Washing Step

Next, the B3 step (food materials ozonized water washing step) is a stepin which only the ozonized water is sprayed over the whole length T ofthe washing tank 1 and washing is performed. This is adopted in a casewhere food materials are not very contaminated, and sterilization andwashing is a main object. Water spray of the ozonized water is performedfrom not only the second wash water piping 2 but also the first washwater piping 9. In this case, the valves V1, V4 and V6 are set “opened”,the valves V2, V3 and V5 are set “closed”, and the pump P2 is activated.Then, the ozonized water in the ozonized water tank 12 is suppliedthrough the piping 58 and the pump P2 to the piping 59, and is dividedthere into two flows. Part of the ozonized water is supplied through thevalve V6, and the pipings 59 b and 56 to the second wash water piping 2,and then, is sprayed to the rear half portion D of the washing tank 1.The remainder of the ozonized water is supplied from the pipings 57 and62 to the first wash water piping 9 through the piping 59 a and thevalves V1 and V4, and is sprayed to the front half portion U in thewashing tank 1. By this, the ozonized water washing of the foodmaterials is performed over the whole length of the washing tank 1.

Also in this case, in order to raise the washing efficiency, the swingoperation may be performed in which the normal rotation and reverserotation of the washing tank are suitably repeated in the state wherethe ozonized water is stayed in the washing tank 1.

Incidentally, in the above food materials washing process (B process),the throughput of food materials per unit time is proportional to therotation speed of the washing tank 1. Thus, the amount of ozonized watersprayed is also adjusted in accordance with the throughput. Theadjustment of the amount of ozonized water supply is basically performedby control of the revolution speed of the pump P2. However, according tocircumstances, there is a case where it is required to treat a largeamount of food materials exceeding the maximum drain rate of the pump P2in a short time. With respect to only the throughput of food materials,if a staying time of the food materials in the washing tank 1 isshortened by raising the revolution speed of the washing tank 1, thethroughput of food materials per unit time can be increased. However,feeding can not be performed in a state where the amount of ozonizedwater supply exceeds the maximum drain rate of the pump P2. Then, inorder to deal with such a situation, the invention adopts the followingstructure. A branch piping 52 a is disposed to the piping 38 for feedingthe ozonized water to the ozonized water tank 12 from the ozonized watergenerator 10. This is connected to a suitable place at the drain side ofthe pump P2. The branch piping 52 a is provided with a valve V7.Accordingly, in the case where a large quantity of ozonized water istemporarily required, the valve V7 is set “opened”. Part of the ozonizedwater supplied to the ozonized water tank 12 from the ozonized watergenerator 10 is divided by the piping 52 a. An amount of divided flow issupplied to the piping 56 at the drain side of the pump P2. By this, thedivided flow of the ozonized water joins the ozonized water fed from theozonized water tank 12. An amount of joined ozonized water is suppliedfrom the piping 56 to the ozonized water piping 2. By this, it becomespossible that the ozonized water more than the ozonized water fed fromthe pump P2 is supplied to the second wash water piping 2.

Incidentally, in the case where the ozonized water is supplied also tothe first wash water piping 9, the valves V1, V4 and V5 are set“opened”. Then, the flow of the ozonized water supplied through thevalves V1 and V4 and the pipings 57 and 62 to the first wash waterpiping 9 joins part of the ozonized water supplied from the piping 52 athrough the valve V5. Then, the joined ozonized water is supplied to thefirst wash water piping 9.

This branch piping 52 a has various use modes. For example, in the casewhere the throughput of food materials is small, the pump P2 is stopped,the valves V1, V5 and V6 are set “closed”, and the valves V7 and V8 areset “opened”. By this, a predetermined quantity of ozonized water isdirectly supplied to the ozonized water piping 2 from the branch piping52 a through the piping 56, and the remainder of the ozonized water canbe stored in the ozonized water tank 12 through the valve V8 and thepiping 52 b. However, in general, the following mode is preferable. Thevalve V7 is set “closed”, the ozonized water in the ozonized water tank12 is supplied to the second wash water piping 2, and surplus ozonizedwater is stored in the ozonized water tank.

Incidentally, the foregoing B1, B2 and B3 steps can be singly carriedout in the food materials washing process. However, in the foodmaterials washing process, it is also possible to carry out these stepsby combining and changing over them. In this case, it is necessary thatwhile the food materials put from the inlet 5 exist in at least thefront half portion U of the washing tank 1, changeover of one cycle iscompleted. For example, in the case where alternate changeover isperformed between the B2 step (alkaline water washing+ozonized waterwashing) and the B1 step (water washing+ozonized water washing), while ablock of specific food materials inputted in the washing tank 1 from theinlet 5 exists in the front half portion U of the washing tank 1, thealkaline water washing and the clean water washing are performed.Thereafter, the block of the food materials is conveyed to the rear halfportion D of the washing tank 1.

Washing Tank After-washing

When the washing of a specified amount of food materials is ended in themanner as described above, finally, the procedure proceeds to theafter-washing process (C process) of the washing tank 1. As stepsperformed in this process, there are following steps, and these stepsare suitably selected and performed: “Alkali after-washing step ofwashing tank” (C1 step) in which the washing tank is washed by alkalinewater; “Water after-washing step of washing tank” (C2 step) in which thewashing tank is washed by clean water; and “alkaline water and waterafter-washing step washing tank” (C3 step) in which after the alkalinewater washing (C1 step) is performed, clean water washing (C2 step) isperformed. Incidentally, since the C1, C2 and C3 steps are identical tothe A1, A2 and A3 steps, the detailed description is omitted.

Cyclic Use of Drain Wash Water

In the above respective processes, the ozonized water, the alkalinewater or the clean water drained from the washing tank 1 flows down intothe drainage receiving tank a disposed below the washing tank 1. Thereceiving tank 8 is constituted by a front receiving tank 8 a and a rearreceiving tank 8 b. The front receiving tank 8 a receives drainage fromthe front half portion U of the washing tank 1. The rear receiving tank8 b receives drainage from the rear half portion D of the washing tank1. The drain wash water flowing down into the front receiving tank 8 ais drained through a piping 71, a valve V11 and a piping 74 to adrainage groove (not shown). The drain wash water flowing down to therear receiving tank 8 b is drained through a piping 72, a valve V12 anda piping 78 to the drainage groove. However, it is also possible tocyclically use the drain wash water flowing down to the receiving tanks8 a and 8 b. A case of cyclic use will be described below.

First, a description will be given of an ozonized water recycle step inthe case where the B2 step (food materials ozonized water washing step)is adopted in the B process “food materials washing process”. In thisstep, the ozonized water is sprayed from both the first and the secondwash water pipings 9 and 2 into the washing tank 1. Since the foodmaterials are sequentially washed while they are conveyed from the fronthalf portion U of the washing tank 1 to the rear half portion D, theozonized water drained from the rear half portion D is less contaminatedthan the ozonized water drained from the front half portion U.Accordingly, the ozonized water drained from the rear half portion D andflowing down to the rear receiving tank 8 b can also be used for washingof the food materials in the front half portion U.

In this step, the valves V1 to V5 of the piping system for supplying theozonized water from the ozonized water tank 12 and the ozonized watergenerator 10 to the first wash water piping 9 are set “closed”, thevalve V6 of the piping system for supplying the ozonized water to thesecond wash water piping 2 is set “opened”, the valve V12 of the drainwash water piping system in the rear receiving tank 8 b is set “closed”,a valve V9 is set “opened”, and a pump P4 is actuated, Then, theozonized water drained from the rear half portion D of the washing tank1 and stored in the rear receiving tank 8 b is supplied to a filterdevice 91 through the pipings 72 and 79. Here, solid matter included inthe drain ozonized water is removed. Subsequently, the ozonized water issupplied to the first wash water piping 9 through the pump P4, thepipings 79 and 75, the valve V9, and the piping 62, and is sprayed tothe front half portion U of the washing tank 1. Incidentally, since theozonized water in the rear receiving tank 8 b is ozonized water which ishardly contaminated, the filter device 91 is not necessarily required.However, in the case where mixture of dust is expected, it is preferableto dispose the filter device 91.

Besides, the ozonized water flowing down from the front half portion Uand stored in the front receiving tank 8 a is made to flow out to theforegoing drainage groove through the piping 71, the valve V11 and thepiping 74. However, it can also be used as materials water of theozonized water generator 10. In this case, the valve V11 is set“closed”, a valve V10 is set “opened”, and the pump P3 is actuated.Then, the drain ozonized water stored in the front receiving tank 8 aflows to the filter device 90 from the piping 71 through a piping 73.Solid matter, such as soil particles, contained in the drain ozonizedwater is removed there. The drain ozonized water joins the materialswater piping 51 through the pump P3, the valve V10 and a piping 77, andis returned to the ozonized water generator 10 through the foregoingwater softener 11. The filter device 90 treats the ozonized waterdrained from the front half portion U of the washing tank 1 in which thefood materials are first washed. According to the state of the foodmaterials, there are various food materials from one which is previouslysubjected to water washing prior to shipping and is relatively lesscontaminated, to one which is seen to be contaminated noticeably withadherent soil. However, most of them are washed and the dirt is removedbefore they are put on the market, Accordingly, the ozonized waterdrained from the front half portion U is not contaminated noticeably,and a small quantity of contained soil is also deposited in the frontreceiving tank 8 a. Further, even if some inorganic particles such assoil particles are contained, there is no influence on the ozonizedwater generator. Apart from the case of heavy dirty, the filter device90 is not necessarily indispensable. In this connection, the frontreceiving tank 8 a is subdivided, drain ozonized water at the mostupstream side in which contamination of drainage is heaviest is drainedto the drainage groove, and only drain ozonized water at the midstreamand the following in which the contamination is relatively low can bereturned to the ozonized water generator. In this case, according to thedegree of contamination of the drain ozonized water, it is also possibleto omit the filter device 90.

Incidentally, all of the drain ozonized water in the rear receiving tank8 b are not supplied to the first wash water piping 9, but only a partis supplied, and the remainder of the drain ozonized water can bereturned to the materials water inlet piping 51 of the ozonized watergenerator 10 through a piping 80, a valve V13, and the piping 77. Inthis case, the ozonized water supplied to the first wash water piping 9through the piping 75, the valve V9, and the piping 62 is decreased.Accordingly, similarly to the foregoing case, it is also possible toadopt a method in which the fresh ozonized water in the ozonized watertank 12 is supplied to the piping 62 through the piping 58, the pump P2,the pipings 59 and 59 a, the valves V1 and V4 and the piping 57.

Incidentally, other than the ozonized water, alkaline water or cleanwater is sprayed in a process as set forth below. In the case of“Alkaline water before-washing step of washing tank” (A1 step) in thewashing process of the washing tank 1, “alkaline water after-washingstep of washing tank” (C1 step), or the “before-washing step of washingtank” (A2 step), or the “After-washing step of washing tank” (C2 step),the alkaline water or the clean water is sprayed to the front halfportion U of the washing tank 1 and the rear half portion D. Thus, alsoin this case, similarly to the case of the recycle use of the ozonizedwater, it is also possible to recycle the wash water (alkaline water orclean water) flowing down to the rear receiving tank 8 b to the firstwash water piping 9. At the same time, it is also possible to return thewash water flowing down to the receiving tank 8 a to the ozonized watergenerator 10.

Further, in the case where the kind of the wash water is differentbetween the front half portion U of the washing tank 1 and the rear halfportion D, it is impossible to recycle the drain water of the rear halfportion D to the front half portion U. However, it is possible to returnthe wash water in the front receiving tank 8 a or the rear receivingtank 8 b to the materials water inlet side of the ozonized watergenerator 10. For example, in the “food materials washing process” (Bprocess), and in the “Pre-washing and washing step of food materials”(B1 step) in which the clean water is sprayed to the front half portionU, and the ozonized water is sprayed to the rear half portion D, or inthe “food materials degreasing and washing step” (B2 step) in which thealkaline water is sprayed to the front half portion U and the ozonizedwater is sprayed to the rear half portion D, the wash water in the frontreceiving tank 8 a or the rear receiving tank 8 b can be returned to thematerials water inlet side of the ozonized water generator 10.Specifically, in the case where the wash water is returned from thefront receiving tank 8 a, the valve V11 is set “closed”, the valve V10is set “opened”, and the pump P3 is actuated. Then, the drain wash waterin the receiving tank 8 a enters the filter member 90 disposed in thepiping 73 through the piping 71. Solid matter is removed there from thedrain wash water. The drain wash water is returned to the materialswater piping 51 through the pump P3 and the piping 77. On the otherhand, in the case where it is returned from the rear receiving tank 8 b,the valves V12 and V9 are set “closed”, the valve V13 is set “opened”,and the pump P4 is activated. Then, the drain wash water in thereceiving tank 8 b enters the filter member 91 of the piping 79 throughthe piping 72. Solid matter in the drain wash water is removed there.The drain wash water is returned to the materials water piping 51 by thepump P4 through the piping 80, the valve V13 and the piping 77.Incidentally, it is also possible to return the drain wash water in boththe front receiving tank 8 a and the rear receiving tank 8 b to thematerials water inlet side of the ozonized water generator 10. In thiscase, it becomes possible to suppress the use of the fresh clean watersupplied from the materials water supply piping 51 to the minimum.

Incidentally, the changeover operation of the valves in the abovedescription, the operation of the activation and stop of the pumps, andthe rotation operation of the washing tank are all controlledautomatically based on previously inputted control values. The controlvalues are previously inputted to a control plate 60 installed at theapparatus side.

Besides, in the above embodiment, the second wash water piping 2 and thefirst wash water piping 9 are constituted by the double pipe 14.However, the second wash water piping 2 and the first wash water piping9 are respectively independent from each other and may be disposed inparallel at the center of the washing tank 1. In this case, the waterspray holes 2 a are bored only in the rear half portion of the firstwash water piping 2, and the water spray holes 9 a are bored only in thefront half portion of the first wash water piping 9. By that, it ispossible to spray the alkaline water, the ozonized water and the cleanwater quite similarly to the case of the double pipe. Besides, waterspray holes may be formed over the whole length of both the wash waterpipings 2 and 9 disposed to be parallel with each other. In this case,in the “food materials washing step”, by a timer operation of the valve,the ozonized water and the clean water or the alkaline water arealternately sprayed every predetermined time, for example, everyrotation of the washing tank 1.

Besides, the second wash water piping 2 and the first wash water piping9 may be constituted by one common piping, In this case, in the “foodmaterials washing step”, the ozonized water and the clean water or thealkaline water are alternately made to flow by an automatic valveoperation, and the changeover is performed every rotation of the washingtank 1. In brief, in the invention, the way of changing over theozonized water, the clean water and the alkaline water and the form ofthe pipings are basically arbitrary. Also in the before-washing processof the washing tank 1 and the after-washing step of washing tank, whichare performed before and after the washing step of food materials,washing can also be performed by the ozonized water. The invention isnot limited to the flow shown in FIG. 8.

Besides, in the illustrated apparatus, the spiral member 3 is disposedin the washing tank 1, and with the rotation of the washing tank 1, foodmaterials are automatically sent from the inlet to the outlet. Such anapparatus is effective in the case where a large amount of foodmaterials are continuously subjected to a washing treatment. However, inthe case where a small amount of food materials is subjected to a batchprocessing, the spiral member is not required. In this case, the washingtank 1 is horizontally installed, and both ends are hermetically sealedor a weir is formed to such a degree that inside water does not flowout, and further, an openable door is provided at the drainage part 4 ofthe washing tank 1. At the time of washing, the door of the drainagepart 4 is opened, and the food materials are put in the inside. Afterthis is closed, while the washing tank 1 is rotated, the ozonized wateris sprayed and the washing of the food materials is performed. After thewashing, the drainage part 4 is positioned down, and when the door isopened, the food materials drop into the receiving basket.

Further, the shape of the spiral member 3 may be a discontinuous spiralin which the continuous spiral is partially cut, in addition to thecontinuous spiral. Especially in the case of the discontinuous spiral,the spiral member must be formed such that it becomes a weir for causingthe ozonized water to stay in at least the bottom when the drainage part4 is positioned up by the rotation of the washing tank 1.

Besides, in the illustrated apparatus, the ozonized water generated bythe ozonized water generator 10 is once supplied to the ozonized watertank 12. Since the ozonized water is once stored in the ozonized watertank 12, it becomes unnecessary to frequently perform the control of theozonized water generator. Thus, it is practical. However, direct feedingmay be performed from the ozonized water generator 10 to the second washtank piping 2 or the like. In this case, in accordance with the amountof ozonized water demanded, the amount of materials water supply to theozonized water generator 10 is adjusted so that the amount of ozonizedwater generated is adjusted. Thus, the ozonized water tank 12 becomesunnecessary, and reduction in installation cost becomes possible.

EXAMPLE 1

Next, a washing test of cut vegetables using ozonized water by themethod and the apparatus of the invention will be described. Thesectional shape of a small washing tank used for the test is a regularhexagon having one side of 150 mm. The small washing tank used for thetest is a hexagonal cylinder having a length of 500 mm. A piping of 40mm φ (diameter) is disposed at its center in a longitudinal direction.One surface of the hexagonal cylinder is a porous plate in which a largenumber of small holes are bored, This constitutes a drainage part. Thiswashing tank was used and the washing test was carried out under thefollowing conditions.

(1) Sample: cut cucumber of 2 kg

(2) Washing method: The cut cucumber of 2 kg was put in the abovewashing tank for the test, and while the washing tank was rotated at arevolution speed of 30 rpm, the washing test was carried out as follows:

<1> water washing: water was sprayed from the above piping for oneminute (about 40 liters) to perform water washing,

<2> ozonized water washing: ozonized water with an ozone concentrationof 10 ppm was sprayed at a flow rate of 53 liters/minute to performwashing, and

<3> sampling: sampling was performed at two places before the waterwashing, after the water washing, at a point of time when 90 seconds(one minute and a half, ozonized water flow of 80 liters) passed, and apoint of time when 180 seconds (three minutes, ozonized water flow of160 liters) passed.

(3) Sterilization estimation: general live bacteria of the sampled cutcucumber was cultivated in a standard agar medium, the number wascounted, and its average value was obtained. The results are as follows:Incidentally, a left numerical value in a parenthesis indicates a valuewhen a state before the water washing is made 100%, and a rightnumerical value indicates a value when a state after the water washingis made 100%.

<1> before the water washing: 3080 thousand (100%, - - - )

<2> after the water washing; 737.5 thousand (23.9%, 100%)

<3> after the ozonized water washing for 90 seconds: 62.5 thousand(2.0%, 8.4%)

<4> after the ozonized water washing for 180 seconds: 57.1 thousand(1.8%, 7.7%)

As is apparent from the above test results, by the ozonized waterwashing for one minute and a half, as compared with the state before thewater washing, which is the state of raw vegetables, the number of livebacteria decreases to about 2%. As compared with the case of only thewater washing, the number of bacteria decreases to 7% or more and 8% orlower. From this, it is understood that the number of live bacteria canbe reduced (sterilized) to about 2% in the ozonized water washing forone minute or more and two minutes or lower. In this meaning, it becomespossible to perform necessary washing with a small quantity of washwater (ozonized water), and it may be gathered that a great saving ofwater resources also becomes possible.

EXAMPLE 2

A test was carried out as follows: Two small washing tanks used for theexample 1 were coupled, ozonized water was sprayed to each of them, anddrain ozonized water from the rear half portion was recycled to theformer half portion drain ozonized water from the front half portion wasreturned to the materials water inlet side of the electrolytic ozonizedwater generator. Test conditions are as follows:

(1) Electrolytic ozonized water generator

<1> amount of ozonized water (concentration of 10 ppm) generated: 25liters/minute

<2> amount of alkaline water generated: 3 liters/minute (not used butdrained)

(2) Sample: cut lettuce (shredded in the order of a size of a humanhand)

(3) washing method: The cut lettuce was put in the above washing tank ata speed of 100 kg/hr, and while the washing tank was rotated at arevolution speed of 30 rpm, ozonized water was sprayed as follows:

<1> rear half portion of the washing tank: fresh ozonized water of aconcentration of 10 ppm generated by the above electrolytic ozonizedwater generator was sprayed at a speed of 25 liters/minute.

<2> front half portion of the washing tank: the whole quantity of drainozonized water draind from the rear half portion of the washing tank wassupplied and sprayed to the front half portion of the washing tank.

(4) Return flow of drain ozonized water; Until the drain ozonized waterdrained from the front half portion of the washing tank is stored in thedrainage receiving tank, tap water is kept supplied to the electrolyticozonized water generator at a flow of 28 liters/minute. At a point oftime when the water of about 50 liters was stored, this was made to passthrough a filter device for removing only solid matter, and return flowto the materials water inlet side of the electrolytic ozonized watergenerator was started at a flow of 25 liters/minute. At the same time,supply of the tap water was changed to a flow of 3 liters/minute.

As a result of the test under the above conditions, the following itemswere confirmed.

(a) The concentration of the drain ozonized water drained from the rearhalf portion of the washing tank decreased to about 2 ppm. However, thedrain ozonized water had sufficient sterilization performance.

(b) With respect to the drain ozonized water drained from the rear halfportion of the washing tank, dirt was not recognized by visualobservation. The drain ozonized water can be directly supplied to thefront half portion.

(c) With respect to the drain ozonized water drained from the front halfportion of the washing tank, soil particles were confirmed though theywere few. However, if only the solid particles are removed through thefilter device, it may be returned to the inlet side of the electrolyticozonized water generator. There is no problem in the operation of theelectrolytic ozonized water generator, and ozonized water of a setconcentration (10 ppm) can be stably generated.

As is apparent from the test results, the drain ozonized water can bereturned to the electrolytic ozonized water generator. By this, itbecomes possible to greatly decrease (reduction of about 90%) the amountof the tap water used from 28 liters/minute to 3 liters/minute.Incidentally, in the above example, although all the alkaline watergenerated by the electrolytic ozonized water generator is drained, asdescribed above, this alkaline water can also be used. Besides, if thisalkaline water is also returned to the inlet side of the electrolyticozonized water generator, a cyclic use of approximately 100% becomespossible. Accordingly, the clean water such as the tap water is suppliedonly at the beginning, and only the clean water corresponding to aleakage amount from the washing apparatus has only to be supplied duringthe washing operation. A great reduction in the amount of wash waterused can be expected.

As described above, according to the food materials washing apparatus ofthe invention, the washing tank 1 is formed into the cylindrical body,and while this is rotated, the ozonized water is sprayed, and therenewal of the ozonized water is performed every rotation of the washingtank 1. Thus, it becomes possible to realize a sufficient washingsterilization effect by a small quantity of ozonized water.

Especially, if the spiral member 3 is disposed in the washing tank 1,with the rotation of the washing tank 1, food materials put in thewashing tank are subjected to washing by the ozonized water, and areautomatically conveyed from the inlet side to the outlet side. Thus, itbecomes possible to continuously perform the washing treatment of alarge amount of food materials, and as compared with a conventionalbatch processing method, it becomes possible to perform the washingtreatment in a short time. As a result, in a large restaurant, a giantcenter for supply of food or the like, even in the case where foodmaterials for several thousand people per day are subjected to thewashing treatment, it becomes possible to perform the treatmentcollectively in a short time.

In addition, even in the case where harmful bacteria such as O-157 stickon the food materials and the bacteria generate toxin, not only thebacteria are sterilized by the ozonized water, but also the toxic matteris oxidized and dissolved, and therefore, it can be said to be a verydesirable sterilization method from the viewpoint of food materialsanitation.

Besides, if the water electrolytic ozonized water generator is adoptedas the ozonized water generating apparatus, alkaline water secondarilygenerated at the cathode side can be used as wash water of the washingtank and food materials. Further, if the alkaline water is made to besprayed from the wash water piping disposed in the washing tank, washingof the washing tank and the food materials becomes possible by thechangeover operation of the valves. Thus, a cleanser and a tool for thewashing of the washing tank become unnecessary, and not only the washingoperation of the washing tank is simplified, but also the use of thecleanser as a cause of environmental pollution becomes unnecessary, andthere is also an effect from a viewpoint of earth environment.

Further, in the case of the mode in which the alkaline water washing andwater washing of the washing tank, and the water washing, alkaline waterwashing and ozonized water washing of the food materials are performedby the automatic changeover operation of the valves, all operations fromthe washing of the washing tank before use to the washing of the foodmaterials and the washing of the washing tank after use are automated.Thus, a great person-saving effect can be expected.

Besides, in the case of the embodiment in which the swing operation bychanging over the normal rotation and reverse rotation in the rotationdirection of the washing tank is performed in the state where thedrainage part is positioned up, the washing can be performed byeffectively using the ozonized water or the like stayed in the lowerpart of the washing tank at the time of the washing process of the foodmaterials and the washing tank. Especially in the case of the foodmaterials, since a turnaround of food materials is performed in thewashing tank by the changeover of the rotation direction, the ozonizedwater or the like permeates every part of the food materials, and thewashing effect can be further raised. Besides, at the same time, theamount of ozonized water used can be reduced by the effective use of theozonized water.

Besides, in the case of the embodiment in which the wash water pipingprovided in the washing tank is connected to both the ozonized watergenerator and the ozonized water tank, and the supply of ozonized watercan be performed from any of them by the changeover operation of thevalves, when there occurs a demand for the ozonized water exceeding theamount of ozonized water generated by the ozonized water generator perunit time or the drain capacity of the ozonized water supply pump of theozonized water tank, it becomes possible to supply the ozonized water tothe washing tank from both. Accordingly, it becomes possible to flexiblydeal with a peak demand without providing a large capacity ozonizedwater generator corresponding to the peak demand for the ozonized water.As a result, installation costs can be reduced.

Further, in the embodiment in which the washing tank is divided into thefront half portion and the rear half portion, the first and the secondwash water pipings for spraying the wash water to each of them aredisposed, and the wash water (ozonized water, alkaline water or cleanwater) used for the rear half portion is recycled to the front halfportion, it is possible to reduce the amount of wash water used toapproximately half. As a result, a great energy-saving andresource-saving effect can be expected.

Further, in the case of the mode in which the ozonized water sprayed tothe washing tank is received by the drain water receiving tank, and thisis returned to the materials water inlet side of the ozonized watergenerator, water recycle of 100% is possible in principle. At least, ascompared with the case where wash water once sprayed is directly draindto a drainage groove, it becomes possible to save water resources atabout 90%. Thus, in a washing workshop of food materials using a largequantity of wash water, a great reduction in cost is enabled, Inaddition, also from the viewpoint of earth environment protection, aremarkable effect can be expected.

INDUSTRIAL APPLICABILITY

As described above, according to the invention, while the ozonized wateris effectively used, the continuous washing and sterilization treatmentof food materials becomes possible. In addition, a harmful toxingenerated by bacteria sticking on the food materials is also madenontoxic by strong oxidizing and dissolving force of the ozonized water.Besides, materials water is also effectively used by the recycle of thewash water. Thus, the food washing apparatus according to the inventionand the washing method are very useful for washing and sterilization ofvarious food materials to be eaten raw, or for washing and sterilizationof food materials before cooking, and for washing and sterilization ofpreserved food materials. Then, a great contribution in food materialsanitation is expected.

1. A food washing apparatus for washing food materials such as foodmaterial stuffs to be eaten raw, grains, tubers, seeds, or nuts by usingozonized water, comprising: an ozonized water generator; a washing tankin which the food materials are put and which can rotate to wash thefood materials, the washing tank having a polygon shaped cross-sectionextending perpendicular to an axis of rotation of the washing tank; adrainage part formed on only one side of the polygon shapedcross-section of the washing tank and including a large number ofopenings to such a degree that water passes through and the foodmaterials do not pass through; and wash water pipings which are disposedin the washing tank in an axial direction and in which water spray holesfor spraying wash water including at least ozonized water generated bythe ozonized water generator into the washing tank are formed, whereinwhile at least part of the wash water sprayed from the wash waterpipings is drained from the washing tank every rotation of the washingtank, washing of the food materials is performed.
 2. A food washingapparatus as set forth in claim 1, further comprising: a receiving tankfor drain wash water drained from the washing tank; and wash waterreturn flow pipings for returning at least one part of the drain washwater in the receiving tank to an inlet side of the ozonized watergenerator, wherein at least one part of the wash water drained from thewashing tank is returned to a materials water inlet side of the ozonizedwater generator.
 3. A food washing apparatus as set forth in claim 2,wherein an inlet for the food materials is disposed at one end of thewashing tank, a outlet for the food materials is formed at the otherend, and a spiral member for conveying, with rotation of the washingtank, the food put in the washing tank from a side of the inlet to theoutlet is disposed on an inner wall surface of the washing tank.
 4. Afood washing apparatus as set forth in claim 3, wherein the spiralmember is a continuous spiral member.
 5. A food washing apparatus as setforth in claim 3, wherein the spiral member is a discontinuous spiralmember.
 6. A food washing apparatus as set forth in claim 3, wherein thewashing tank is obliquely disposed to have a falling gradient from aside of the inlet to a side of the outlet.
 7. A flood washing apparatusas set forth in claim 2, wherein the drainage part is formed to becontinuous in a longitudinal direction of the washing tank, and thewhole quantity of the sprayed ozonized water is drained every rotationof the washing tank.
 8. A food washing apparatus as set forth in claim2, wherein the drainage part is formed intermittently in a longitudinaldirection of the washing tank, and part of the sprayed ozonized water isdrained every rotation of the washing tank.
 9. A food washing apparatusas set, forth in claim 2, wherein the drainage part is formed of a wirenet or a porous metal plate.
 10. A food washing apparatus as set forthin claim 2, wherein the polygon shaped cross-section of the washing tankis a hexagonal shaped cross-section.
 11. A food washing apparatus as setforth in claim 2, wherein the wash water pipings are made rotatable, andby this, a water spray angle of the ozonized water from the water sprayholes of the wash water pipings is made variable.
 12. A food washingapparatus as set forth in claim 2, wherein the washing tank isconstructed so that normal and reverse rotations can be made.
 13. A foodwashing apparatus as set forth in claim 2, wherein the wash waterpipings are constituted by a first wash water piping including a waterspray hole in a front half portion of the washing tank and a second washwater piping including a water spray hole in a rear half portion of thewashing tank, and one of ozonized water and clean water is enabled toflow through both the wash water pipings by a changeover operation ofvalves.
 14. A food washing apparatus as set forth in claim 13, whereinin the front half portion of the washing tank, the second wash waterpiping and the first wash water piping are formed of a double pipe. 15.A food washing apparatus as set forth in claim 13, wherein the receivingtank of the wash water is constituted by a front receiving tank for washwater drained from, the front half portion of the washing tank and arear receiving tank for wash water drained from the rear half portion.16. A food washing apparatus as set forth in claim 15, wherein washwater reuse pipings for supplying at least one part of drain wash waterin the rear half receiving tank to an inlet side of the first wash waterpiping.
 17. A food washing apparatus as set forth in claim 15, whereinwash water return flow pipings for returning at least one part of thedrain wash water in the rear receiving tank to the inlet side of theozonized water generator are provided.
 18. A food washing apparatus asset forth in claim 15, wherein wash water return flow pipings forreturning at least one part of the drain wash water in the frontreceiving tank to the inlet side of the ozonized water generator areprovided.
 19. A food washing apparatus as set forth in claim 13, whereinan ozonized water tank for storing the ozonized water fed from theozonized water generator is disposed, at least the second wash waterpiping is connected to both the ozonized water generator and theozonized water tank, and the ozonized water is enabled to be supplied toat least the second wash water piping from one of or both of theozonized water generator and the ozonized water tank by a changeoveroperation of valves.
 20. A food washing apparatus as set forth in claim2, wherein the wash water pipings are constituted by a first wash waterpiping including a water spray hole in a front half portion of thewashing tank and a second wash water piping including a water spray holein a rear half portion of the washing tank, the ozonized water isozonized water generated at an anode side by an electrolysis method ofwater, and one of the ozonized water, alkaline water generated at acathode side by the electrolysis method, and clean water is enabled toflow through both the wash water pipings by a changeover operation ofvalves.
 21. A food washing apparatus as set forth in claim 2, wherein inthe front half portion of the washing tank, the second wash water pipingand the first wash water piping are formed of a double pipe.
 22. A foodwashing apparatus as set-forth in claim 2, wherein the washing tank isconstituted by coupling unit cylinders in each of which a spiral memberis formed along an inner wall, to be separable in a longitudinaldirection.
 23. A food washing apparatus as set forth in claim 1, whereinan inlet for the food materials is disposed at one end of the washingtank, a outlet for the food materials is formed at the other end, and aspiral member for conveying, with rotation of the washing tank, the foodput in the washing tank from a side of the inlet to the outlet isdisposed on an inner wall surface of the washing tank.
 24. A foodwashing apparatus as set forth in claim 23, wherein the spiral member isa continuous spiral member.
 25. A food washing apparatus as set forth inclaim 23, wherein the spiral member is a discontinuous spiral member.26. A food washing apparatus as set forth in claim 23, wherein thewashing tank is obliquely disposed to have a falling gradient from aside of the inlet to a side of the outlet.
 27. A food washing apparatusas set forth in claim 1, wherein the drainage part is formed to becontinuous in a longitudinal direction of the washing tank, and thewhole quantity of the sprayed ozonized water is drained every rotationof the washing tank.
 28. A food washing apparatus as set forth in claim1, wherein the drainage part is formed intermittently in a longitudinaldirection of the washing tank, and part of the sprayed ozonized water isdrained every rotation of the washing tank.
 29. A food washing apparatusas set, forth in claim 1, wherein the drainage part is formed of a wirenet or a porous metal plate.
 30. A food washing apparatus as set forthin claim 1, wherein the polygon shaped cross-section of the washing tankis a hexagonal shaped cross-section.
 31. A food washing apparatus as setforth in claim 1, wherein the washing tank is constructed so that normaland reverse rotations can be made.
 32. A food washing apparatus as setforth in claim 1, wherein the wash water pipings are constituted by afirst wash water piping including a water spray hole in a front halfportion of the washing tank and a second wash water piping including awater spray hole in a rear half portion of the washing tank, and one ofozonized water and clean water is enabled to flow through both the washwater pipings by a changeover operation of valves.
 33. A food washingapparatus as set forth in claim 32, wherein in the front half portion ofthe washing tank, the second wash water piping and the first wash waterpiping are formed of a double pipe.
 34. A food washing apparatus as setforth in claim 32, wherein the receiving tank of the wash water isconstituted by a front receiving tank for wash water drained from thefront half portion of the washing tank and a rear receiving tank forwash water drained from the rear half portion.
 35. A food washingapparatus as set forth in claim 34, wherein wash water reuse pipings forsupplying at least one part of drain wash water in the rear halfreceiving tank to an inlet side of the first wash water piping.
 36. Afood washing apparatus as set forth in claim 34, wherein wash waterreturn flow pipings for returning at least one part of the drain washwater in the rear receiving tank to the inlet side of the ozonized watergenerator are provided.
 37. A food washing apparatus as set forth inclaim 34, wherein wash water return flow pipings for returning at leastone part of the drain wash water in the front receiving tank to theinlet side of the ozonized water generator are provided.
 38. A foodwashing apparatus as set forth in claim 32, wherein an ozonized watertank for storing the ozonized water fed from the ozonized watergenerator is disposed, at least the second wash water piping isconnected to both the ozonized water generator and the ozonized watertank, and the ozonized water is enabled to be supplied to at least thesecond wash water piping from one of or both of the ozonized watergenerator and the ozonized water tank by a changeover operation ofvalves.
 39. A food washing apparatus as set forth in claim 1, whereinthe wash water pipings are constituted by a first wash water pipingincluding a water spray hole in a front half portion of the washing tankand a second wash water piping including a water spray hole in a rearhalf portion of the washing tank, the ozonized water is ozonized watergenerated at an anode side by an electrolysis method of water, and oneof the ozonized water, alkaline water generated at a cathode side by theelectrolysis method, and clean water is enabled to flow through both thewash water pipings by a changeover operation of valves.
 40. A foodwashing apparatus as set-forth in claim 1, wherein the washing tank isconstituted by coupling unit cylinders in each of which a spiral memberis formed along an inner wall, to be separable in a longitudinaldirection.
 41. A food washing apparatus for washing food materials suchas food material stuffs to be eaten raw, grains, tubers, seeds, or nuts,by using ozonized water, comprising: an ozonized water generator forgenerating ozonized water at an anode side by electrolysis of water andfor generating alkaline water at a cathode side; an ozonized water tankfor storing the ozonized water generated at the anode side by theozonized water generator; an alkaline water tank for storing thealkaline water generated at the cathode side by the ozonized watergenerator; a rotatable cylindrical washing tank in which a drainage partincluding a large number of openings to such a degree that water passesthrough and the food materials do not pass through is formed in alongitudinal direction; and a second wash water piping which is disposedto pass through substantially a center part of the washing tank in anaxial direction and in which a large number of water spray holes areformed at a place corresponding to a rear half portion of the washingtank; a first wash water piping which is an outside pipe of a doublepipe having the second wash water piping as an inside pipe and formed ata place corresponding to a front half portion of the washing tank, andincludes a large number of water spray holes formed in an axialdirection, the outside pipe and the inside pipe being coaxial andcoextensive for a portion thereof; and a piping system capable ofsupplying the ozonized water, the alkaline water and clean water to eachof the second wash water piping and the first wash water piping by achangeover operation of valves, wherein while at least one part of washwater sprayed from the first and the second wash water pipings isdrained from the washing tank every rotation of the washing tank,washing of the food materials is performed.
 42. A food washing apparatusas set forth in claim 41, comprising: a front receiving tank for drainwash water from the front half portion of the washing tank; a rearreceiving tank for drain wash water from the rear-half portion of thewashing tank; and a piping system-for enabling the drain wash water inthe rear receiving tank to be supplied to the first wash water piping,wherein at least one part of wash water used in the rear half portioncan be used as wash water of the front half portion.
 43. A food washingapparatus as set forth in claim 41, comprising a piping system forenabling drain wash water in the front receiving tank or drain washwater in the rear receiving tank to be returned to the inlet side of theozonized water generator, wherein at least one part of wash waterdrained from the washing tank is enabled to be used as materials waterof the ozonized water generator.
 44. A food washing apparatus asset-forth in claim 41, wherein the washing tank is constituted bycoupling unit cylinders in each of which a spiral member is formed alongan inner wall, to be separable in a longitudinal direction.
 45. A foodwashing method for washing food materials such as food material stuffsto be eaten raw, grains, tubers, seeds, or nuts by using ozonized water,comprising: placing food materials in from an inlet disposed at one endof a washing tank having a polygon shaped cross-section extendingperpendicular to an axis of rotation of the washing tank, the foodmaterials are drained from an outlet formed at the other end of thewashing tank by rotating the washing tank; spraying ozonized water froma wash water piping disposed in an axial direction in the washing tank,and draining the ozonized water by rotation of the washing tank from adrainage part formed on only one side of the polygon shapedcross-section of the washing tank and including an opening to such adegree that water passes through and the food materials do not passthrough, wherein while at least one part of the ozonized water sprayedfrom the wash water piping is drained from the drainage part of thewashing tank every rotation of the washing tank, the food materials arewashed and conveyed.
 46. A food washing method as set forth in claim 45,wherein at least one part of the ozonized water drained from the washingtank is returned to a materials water inlet side of an ozonized watergenerator configured to supply the ozonized water to the wash waterpiping, and the ozonized water is cyclically used.
 47. A food washingmethod as set forth in claim 45, wherein the wash water piping isconstituted by a first wash water piping having a water spray hole in afront half portion of the washing tank and a second wash water pipinghaving a water spray hole in a rear half portion of the washing tank,the ozonized water is ozonized water generated at an anode side by anelectrolysis method of water, and one of the ozonized water, alkalinewater generated at a cathode side by the electrolysis method, and cleanwater is enabled to flow through each of the first and the second washwater pipings by a changeover operation of valves.
 48. A food washingmethod as set forth in claim 47, comprising the following processes: Aprocess: “Before-washing process of washing tank” in which while thealkaline water generated at the cathode side by the electrolysis methodor the clean water is sprayed from one of or both of the first and thesecond wash water pipings, before-washing of the washing tank itself isperformed; B process: “food materials washing process” in which the foodmaterials are put in from the inlet while the washing tank is rotated,and water spray of the ozonized water is performed from at least thesecond wash water piping, so that while at least one part of the sprayedozonized water is drained every rotation of the washing tank, the foodmaterials are conveyed in the washing tank, and washing andsterilization are performed; and C process: “After-washing process ofwashing tank” in which after completion of the food materials washingprocess, while the alkaline water or the clean water is sprayed from oneof or both of the first and the second wash water pipings, after-washingof the washing tank itself is performed.
 49. A food washing method asset forth in claim 48, wherein the A process comprises at least one offollowing A1 step to A3 step: A1 step: “Alkaline water before-washingstep of washing tank” in which the alkaline water is supplied to boththe first and the second wash water pipings to perform alkaline waterwashing of the washing tank; A2 step: “water before-washing step ofwashing tank” in which the clean water is supplied to both the first andthe second wash water pipings to perform water washing of the washingtank; and A3 step: “alkaline water and water before-washing step ofwashing tank” in which the A2 step is performed after the A1 step isperformed.
 50. A food washing method as set forth in claim 48, whereinthe B process comprises at least one of following B1 step to B3 step: B1step: “Pre-washing and washing step of food materials” in which theclean water is sprayed from the first wash water piping in the fronthalf portion of the washing tank, and the ozonized water is sprayed fromthe second wash water piping in the rear half portion of the washingtank; B2 step: “food materials degreasing and washing step” in which thealkaline water is sprayed from the first wash water piping in the fronthalf portion of the washing tank, and the ozonized water is sprayed fromthe second wash water piping in the rear half portion of the washingtank; and B3 step: “food materials ozonized water washing step” in whichthe ozonized water is sprayed from the second wash water piping to therear half portion of the washing tank, and the ozonized water is sprayedfrom the first wash water piping to the front half portion as well. 51.A food washing method as set forth in claim 50, wherein in the B3 step,the drain ozonized water sprayed from the second wash water piping tothe rear half portion of the washing tank and drained from the rear halfportion of the washing tank is supplied to the first wash water pipingand is sprayed from the first wash water piping to the front halfportion of the washing tank, so that recycle of the ozonized water isperformed.
 52. A food washing method as set forth in claim 48, whereinthe C process, comprises at least one of following C1 step to C3 step:C1 step: “Alkaline water after-washing step of washing tank” in whichthe alkaline water is supplied to both the first and the second washwater pipings to perform alkaline water washing of the washing tank; C2step: “Water after-washing step of washing tank” in which the cleanwater is supplied to both the first and the second wash water pipings toperform water washing of the washing tank; and C3 step: “Alkaline waterand water after-washing step of washing tank” in which the C2 step isperformed after the C1 step is performed.
 53. A food washing method asset forth in claim 47, wherein the ozonized water drained from the fronthalf portion of the washing tank is returned to the materials waterinlet side of the ozonized water generator.
 54. A food washing method asset forth in claim 47, wherein in at least one of the A process, the Bprocess and the C process, at least one part of the wash water drainedfrom the washing tank is returned to the materials water inlet part ofthe ozonized water generator.
 55. A food washing method as set forth, inclaim 45, wherein in a state where the sprayed wash water is stayed inthe washing tank, a swing operation by rotation direction changeover isperformed at least one time in which a rotation direction of the washingtank is reversed and is next normally rotated.
 56. A food washing methodas set forth in claim 55, wherein a rotation speed of the washing tankat a time of the swing operation is made faster than a rotation speed ata time of non-swing.
 57. A food washing method as set forth in claim 45,wherein an inlet for the food materials is disposed at one end of thewashing tank, a outlet for the food materials is formed at the otherend, and a spiral member for conveying, with rotation of the washingtank, the food materials put-in the washing tank from a side of theinlet to the outlet is disposed on an inner wall surface of the washingtank.